• Industrial Engineering and Management Systems
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• 제7권2호
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• pp.160-170
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• 2008

This paper proposes a mathematical model for converting conveyor assembly line to cellular manufacturing in complex production environments. Complex production environments refer to the situations with multi-products, variant demand, different batch sizes and the worker abilities varying with work stations and products respectively. The model proposed in this paper aims to determine (1) how many cells should be formatted; (2) how many workers should be assigned in each cell; (3) and how many workers should be rested in shortened conveyor line when a conveyor assembly line should be converted, in order to optimize system performances which are defined as the total throughput time and total labor power. We refer the model to a new production system. Such model can be used as an evaluation tool in the cases of (i) when a company wants to change its production system (usually a belt conveyor line) to a new one (including cell manufacturing); (ii) when a company wants to evaluate the performance of its converted system. Simulation experiments based on the data collected from the previous documents are used to estimate the marginal impact that each factor change has had on the estimated performance improvement resulting from the conversion.

• International Journal of Oral Biology
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• 제32권3호
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• pp.93-101
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• 2007

Cell behavior of the transformed cells is known to affect by interaction with extracellular matrix (ECM) proteins and integrin. To investigate the alterations of both integrin expression and cell-matrix interaction during neoplastic conversion of human oral kerationcytes, we studied expression levels of integrin subunits by flow cytometry and cellular responses to the ECM proteins in normal human oral keratinocytes (NHOKs), HPV-immortalized HOK-16B line, and three oral cancer cell lines established from HOK-16B line, CTHOK-16B-BaP, CTHOK-16B-DMBA, and CTHOK-16B-Dexa lines. The expression levels of ${\alpha}\;and\;{\beta}$ integrin subunits were shown decreased tendency in human oral keratinocytes undergoing immortalization and tumorigenic transformation except CTHOK-16B-DMBA line tested. Although ${\alpha}v{\beta}6$ integrin is known to be highly expressed in squamous cell carcinomas, and the altered integrin expression is suspected to be associated with cellular carcinogenesis, ${\alpha}v$ integrin subunit and ${\alpha}v{\beta}6$ integrin did not express in oral cancer cell lines tested. Cell behavior to the ECM proteins in HOK-16B line was generally similar to that of exponentially proliferating NHOKs. The adhesion activity profiles of type I collagen were very similar to that of its laminin counterparts, but fibronectin showed minimal adhesion activity under our conditions compared to the BSA control. The ability of the CTHOK-16B-BaP line to spread upon type I collagen and laminin markedly decreased, but migration was notably increased on type I collagen. In contrast, CTHOK-16B-DMBA and CTHOK-16B-Dexa lines spread less but migrated more upon type I collagen than immortalized HOK-16B line. These data indicate that downregulation of integrin subunits causes the changes of cellular responses to the ECM proteins during neoplastic conversion of human oral keratinocytes, and that cellular responses to the ECM proteins in oral cancer cell lines established by exposing different carcinogens are variable according to chemical carcinogens treatment.

• Biomolecules & Therapeutics
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• 제11권4호
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• pp.238-244
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• 2003

Nicotine is one of the major hazardous components in cigarettc smoke. Nicotine deals a harmful effect to smokers and passive smokers due to its rapid conversion to various carcinogenic metabolites. Nitrosamine-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is believed to cause lung cancers among the nicotine-derived carcinogens. Recent studies report that NNK synthesis can be inhibited by the metabolism pathway to produce a stable metabolite cotinine from nicotine. Tea polyphenols have been known to contain factors to prevent cancers and to retard progression of cancers. This study aims to correlate tea polyphenol's potential for cancer prevention with an accelerated formation of cotinine. The conversion from nicotine to cotinine in the presence of tea extracts or three polyphenols (Catechin, epicatechin gallate, epigallocatechin gallate) was measured in established cell lines and in Xenopus oocytes. Among three lines of cell used, PLC/PRF5 and HEK293 cells showed a fast turnover from nicotine to cotinine while HepG2 cell line showed a marginal difference between groups treated and non-treated with tea polyphenols. When Xenopus oocytes were microinjected with nicotine, tea polyphenols appear to accelerate the conversion of nicotine to cotinine. Among the polyphenols tested in this study, (＋)－catechin showed the best efficiency overall in accelerating conversion from nicotine to cotinine both in the cell lines and in the oocytes. In summary, the present study indicated that tea polyphenols have a positive effect on conversion of nicotine to cotinine.

• Journal of Power Electronics
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• 제13권4호
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• pp.516-527
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• 2013

This paper presents a new overall system for state-of-available-power (SoAP) prediction for a lithium-ion battery pack. The essential part of this method is based on an adaptive network architecture which utilizes both fuzzy model (FIS) and artificial neural network (ANN) into the framework of adaptive neuro-fuzzy inference system (ANFIS). While battery aging proceeds, the system is capable of delivering accurate power prediction not only for room temperature, but also at lower temperatures at which power prediction is most challenging. Due to design property of ANN, the network parameters are adapted on-line to the current battery states (state-of-charge (SoC), state-of-health (SoH), temperature). SoC is required as an input parameter to SoAP module and high accuracy is crucial for a reliable on-line adaptation. Therefore, a reasonable way to determine the battery state variables is proposed applying a combination of several partly different algorithms. Among other SoC boundary estimation methods, robust extended Kalman filter (REKF) for recalibration of amp hour counters was implemented. ANFIS then achieves the SoAP estimation by means of time forward voltage prognosis (TFVP) before a power pulse occurs. The trade-off between computational cost of batch-learning and accuracy during on-line adaptation was optimized resulting in a real-time system with TFVP absolute error less than 1%. The verification was performed on a software-in-the-loop test bench setup using a 53 Ah lithium-ion cell.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.116-120
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• 2011

In this paper, we studied the optimization of the screen pringting method for crystalline silicon solar cell fabrication. The 156 * 156 mm2 p-type silicon wafers with $200{\mu}m$ thickness and $0.5-3{\Omega}cm$ resistivity were used after texturing, doping, and passivation. Screen printing method is a common way to make the c-Si solar cell with low-cost and high-efficiency. We studied the optimized condition for screen printing with crystalline silicon solar cell as changing the printing direction (finger line or bus bar), finger width, and mesh angle. As a result, the screen printing with finger line direction showed higher finger height and better conversion efficiency, compared with one with bus bar direction. The experiments with various finger widths and mesh angles were also carried out. The characteristics of solar cells was obtained by measuring light current-voltage, optical microscope and electroluminescence.

• Journal of Power Electronics
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• 제7권4호
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• pp.328-335
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• 2007

A conventional Single-Stage Power-Factor-Correction (PFC) AC/DC converter has a link capacitor voltage problem under high line input and low load conditions. In this paper, this problem is analyzed by using the voltage conversion ratio of the DC/DC conversion cell. By applying this analysis, a new Single-Stage PFC AC/DC converter with a boost PFC cell integrated with a Voltage-Doubler Rectified Asymmetrical Half-Bridge (VDRAHB) is proposed. The proposed converter features good power factor correction, low current harmonic distortions, tight output regulations and low voltage of the link capacitor. An 85W prototype was implemented to show that it meets harmonic requirements and standards satisfactorily with near unity power factor and high efficiency over universal input.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.5-6
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• 2006

There are typically applied on both rear and front sides of electrical contacts to the solar cell. The front contact formation is particularly sensitive to many parameters. Accordingly patterning of front grid line is an important factor of solar cells. This paper describe the electrical conversion efficiency, inclusive of shading loss that gives various spacing between front metal grid lines. In experiments with variation of spacing. It was verified that the wide spacing of grid fingers could increase the series resistance, also the narrow spacing of grid fingers also implies a grid with a higher density of grid fingers. The sunlight of incidence was more of reflection by grid fingers. In result, the short circuit current, which contribute to conversion efficiency was decreased, because maximum power input was reduced and increase the series resistance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.291-294
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• 1990

Fuel cell system needs DC-AC conversion inverter system because its output is DC. And the inverter system can be operated not only in stand-alone load but also in interactive mode in interactive mode, it is necessary to control active-reactive power of inverter and to synchronize inverter output voltage to power line voltage. In this paper, a 12 phase multiple VSI type GTO inverter system for fuel cell is described. Synchronization between power line voltage phase and inverter output voltage phase, and reduction of harmonics in the output voltage phase are the purpose of this inverter system. This control algorithm for the system is realized by the software method utilizing 8031AH 8bit Microprocessor.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.478-483
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• 2000

In this study to cope with the decreasing product's life-cycle a virtual simulator to realize the simulation environment similar to a real manufacturing line is developed. The developed simulator plays a role in reducing the product conversion time by alternating manufacturing components and work plans on the simulation as manufacturing lines change and actuating a virtual manufacturing lines change and actuating a virtual manufacturing line before a real production. The developed simulator realized a virtual manufacturing line on the simulation using various manipulators and work cells as manufacturing components. Also It can be shown that the simulator can cope with rapid change of a manufacturing line by developing a interface that a separate process is managed for each manufacturing module and a manipulator component and a work cell are changed for a user to become convenient to teach tasks of each work module. using Microsoft Visual C++ 6.0 and OpenGL of Silicon Graphics for libraries to realize 3-dimensional graphic and constructing a database system, a hybrid type of hierachical and relational model to develop a progra that has efficiency and standardization.

• KSBB Journal
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• 제8권1호
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• pp.17-22
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• 1993

$1.96{\times}10^{-5}$(IU/cell/hr) of specific scu-PA production rate was obtained from HEK cells in maintaining ca. $8{\times}10^{5}$(cells/ml) of maximum roll density at 10(ml/hr) of perfusion rate with recycling 20% serum free conditioned media. It can be compared to $4{\times}10^{6}$(cells/ml) of maximum cell density and $4.56{\times}10^{-4}$(IU/cell/hr) of specific production rate in cultivating cells with 1% serum containing medium. Thc conversion ratio of scu-PA to tc-UK increased up to 55% as the recycling ratio increased; however, recycling the used medium seemed to have least negative effect on cell growth. It also showed that the recycling process had definitive advantage of using serum free medium in perfusion cultivation of HEK cell line.